137 lines
4.1 KiB
Python
137 lines
4.1 KiB
Python
import struct
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class PnmImage(object):
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def __init__(self):
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self._filename = None
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self._image = []
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self._version = None
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self._maxval = None
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self._width = 0
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self._height = 0
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def reset(self):
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"""Reset all image data (dims, data,...)"""
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self._filename = None
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self._image = []
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self._version = None
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self._maxval = None
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self._width = 0
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self._height = 0
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def _load_bin_pbm(self, fd):
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"""Load image data from a file of PBM binary format
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:param fd: file descriptor of the file starting to the image data so
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the version and dimensions should have been skipped
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"""
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c = fd.read(1)
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i = 0
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size = self._width * self._height
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while len(c) > 0:
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c = struct.unpack("<B", c)[0]
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# each byte is a bit array of 8 pixels
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for b in range(8):
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if c & 128:
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self._image.append(1)
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else:
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self._image.append(0)
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c <<= 1
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i += 1
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if i >= size:
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break
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if i >= size:
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break
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c = fd.read(1)
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def _load_bin_pgm(self, fd):
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"""Load image data from a file of PGM binary format
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:param fd: file descriptor of the file starting to the image data so
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the version and dimensions should have been skipped
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"""
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maxval = fd.readline().decode("utf-8").strip()
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self._maxval = int(maxval)
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c = fd.read(1)
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while len(c) > 0:
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c = struct.unpack("<B", c)[0]
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self._image.append(c)
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c = fd.read(1)
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def load(self, filename):
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"""Load an image pnm. Managed formats: P4, P5
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:param filename: the image's file name
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:return: False if failed to open the file
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"""
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ret = True
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try:
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fd = open(filename, 'rb')
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except IOError:
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ret = False
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else:
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with fd:
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self.reset()
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self._filename = filename
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self._version = fd.readline().decode("utf-8").strip()
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c = fd.read(1).decode("utf-8")
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if c == "#":
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comment = fd.readline().decode("utf-8").rstrip()
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#print("#{}".format(comment))
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c = ""
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dims = c + fd.readline().decode("utf-8").strip()
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width, height = dims.split(" ")
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self._width = int(width)
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self._height = int(height)
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if self._version == "P5":
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self._load_bin_pgm(fd)
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elif self._version == "P4":
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self._load_bin_pbm(fd)
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return ret
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def get_data(self):
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"""Get the image data in a 1D list"""
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return self._image
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def get_data_bin(self, threshold=125):
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"""Get the image data in a 1D list"""
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return [1 if e < threshold else 0 for e in self._image]
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def get_info(self):
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"""Get the image information
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:return: information in a dict with keys: "version", "dims", "size", "max_value"
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"""
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info = {
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"version": self._version,
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"dims": (self._width, self._height),
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"size": len(self._image),
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"max_value": self._maxval
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}
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return info
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def get_size(self):
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return len(self._image)
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def show_image_info(self):
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print("file: {}".format(self._filename))
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print("version: {}".format(self._version))
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print("dims: {}x{} (={})".format(self._width, self._height, self._width*self._height))
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print("image size: {}".format(len(self._image)))
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print("max val : {}".format(self._maxval))
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print("5 first pixels: {}".format(self._image[:5]))
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print("5 last pixels: {}".format(self._image[-5:]))
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if __name__ == "__main__":
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img = PnmImage()
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img.load("data/ext_ln0_car0.pgm")
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img.show_image_info()
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print()
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img.load("mc_p22.pgm")
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img.show_image_info()
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print()
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img.load("tst.pbm")
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img.show_image_info()
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